[throwaway_4253]

I could be wrong, but I think the GP was commenting specifically about time of day? At idealized midnight the vector between you and the sun goes through the center of the Earth, indicating that increasing altitude takes you away from the Sun, instead of towards it. At idealized Noon, the opposite is true.

[8note]

But the speed at which the earth is approaching the sun makes a biggers difference than your flight of stairs?

[throwaway_4253]

Yeah, I guess that's one way of looking at it; I guess on my first read of the comments I saw it as a related rates problem where "the act of climbing the stairs adds a velocity away from the Sun", but yeah, the second comment makes the case that at certain times of year the sum of the Earth's velocity and your stairs could still be positive in the "towards sun" direction.

(Sigh) this is why I'm poorly suited for Twitter...